<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../react18/react.development.js"></script>
    <script src="../react18/react-dom.development.js"></script>
    <script src="../react18/babel.min.js"></script>
</head>
<body>
    <div id="app"></div>
    <script type="text/babel">
        function Content(){
            return <p>我是内容</p>
        }
    // Component是组成的意思  extends是扩展的意思
        class Title extends React.Component{
    //类式组件必须拥有一个render方法，当组件被使用的时候，组件实例会找render方法拿到返回虚拟DOM
        render(){
            return<h1>标题</h1>
        }
        }
        
        class App extends React.Component{
            render(){
                return(
                <div>   
                <Title/>
                    <hr/>
                    <Content/>
                </div>
                )
            }
        }
      
     const root =ReactDOM.createRoot(document.getElementById("app"));
     root.render(<App/>)
     </script>
</body>
</html>